THE DEVELOPMENTAL OR MYELINOGENETIC REGIONS OF THE HUMAN CEREBRAL CORTEX.

A few years ago Flechsig interested neurologists greatly by his subdivision of the cerebral cortex into primary sense centers on the one hand and association areas on the other. Since that time he has been busily engaged in the further differentiation of the cortex on the basis of successive medullations of the fibers. He now recognizes between thirty and forty definite and distinctly different myelinogenetic regions. He thinks that each myelinogenetic region is provided with a conjugate pair of bundles, one bundle bringing impulses to the area, the other carrying impulses from it. A further view advanced by Flechsig concerns the close relation of the development of the sulci of the brain to that of the medullary sheaths of the various bundles going to the different areas. He distinguishes primary sulci, those which appear very early, from terminal sulci, which are the last to develop. The earliest sulci appear, he